Generator assemblages for motor vehicles typically have an externally excited generator having an excitation winding and a stator winding, a rectifier downstream from the stator winding, and a generator regulator. The generator regulator regulates the voltage generated by the generator by correspondingly adjusting the current through the excitation winding. The generator is often embodied as a claw pole generator. The invention is not limited to use in motor vehicles, however, but can also be utilized in generator assemblages in aircraft and/or watercraft.
The electrical systems of corresponding vehicles encompass at least one generator assemblage, at least one battery, and a plurality of electrical loads. As safety-relevant electrical systems in vehicles become increasingly widespread—for example, the electronic stability program and the like in motor vehicles—protection of the vehicle's electrical system becomes increasingly significant. Protection from overvoltages is particularly important in this context.
Overvoltages can result in particular from electrical faults in the generator assemblage, for example inter-turn short circuits in the stator field, inter-turn short circuits in the excitation winding, changes in the magnetic properties of the electrical machine (for example, as a result of demagnetization of permanent magnets installed therein), short circuits in the rectifier, or faults that influence the no-load voltage of the generator assemblage. “Electrical faults” are understood in the context of this Application as all faults that can influence the voltage introduced into the connected vehicle electrical system by way of the generator assemblage.
As indicated in JP 3374543 B2, voltages present on the DC voltage side and AC voltage side of a rectifier of the generator assemblage can be compared with one another in comparator-based fashion in order to detect electrical faults. The method recited allows a short circuit in the rectifier to be detected, but detection of errors within the generator, for example of inter-turn short circuits in the stator winding or excitation winding thereof, is not possible.
A need therefore continues to exist for improved capabilities for detecting electrical faults in corresponding generator assemblages.